Gas turbine engines draw ambient air from the atmosphere, compress the ambient air, mix the compressed air with a gaseous and/or liquid fuel, and ignite the mixture. As the mixture combusts, heated gases expand and travel at high speed to rotationally drive a turbine section, creating a useful power output. Due to the violent nature of combustion, various engine components may need to be cooled and buffered during operation for durability and engine component longevity. As such, inter-stage bleed ports have been provided within the compressor, where the air is still relatively cool, to draw off a portion of the airflow. The drawn air may then be circulated throughout the engine to provide cooling, buffering, and/or to drive other systems associated with the engine.
Circular bleed ports have been provided for such purposes. Although the circular bleed ports may have provided adequate air-drawing characteristics, bleeding air through such a shape tends to disturb airflow within the compressor flowpath, and, as a result, may reduce engine efficiency and power output. Additionally, a circular shape may not be the most optimum shape for minimizing pressure loss across the ports, which is an important characteristic of the effectiveness of bleed extraction. Therefore, a need existed for bleed ports to provide improved air-drawing characteristics without unduly disturbing airflow through the compressor.
One attempt to improve bleed port air-drawing characteristics is provided by U.S. Patent Application Publication No. 2006/0051199 (the '199 publication) by Guemmer, published on Mar. 9, 2006. Specifically, the '199 publication discloses fluid removal openings of a variety of shapes for a turbo machine. The fluid removal openings of the '199 publication purportedly improved air drawing characteristics between two adjacent vanes. However, the fluid removal openings are positioned in close proximity to a suction side of a first vane, but distant from a pressure side of a second vane. Further, the fluid removal openings are generally convex toward the blade suction side. This arrangement may not suitably reduce disturbances in airflow to the extent necessary to provide a desired level of efficiency and power output. Specifically, the location, shape, and orientation of the fluid removal openings may cause undue aerodynamic losses due to airflow separation between the vanes; particularly, near the suction side of the vanes.
The bleed ports of the present disclosure solve one or more of the problems set forth above.